RE: Matching antenna on circular board

Johannes — Tue, 08 Oct 2019 15:45:13 GMT

Thanks, it makes more sense now.

Andreas — Tue, 08 Oct 2019 13:17:27 GMT

Hi,

Usually there is a reference design for the antenna in the antenna datasheet. This specific part has 3, depending on the feed direction and clearance size.
Yes, the Johanson filter replaces the matching network in our reference design. The performance is very dependent on the layout though, you need to replicate the layout in the filter datasheet as closely as possible with regards to positioning and grounding. You seem to be missing a trace between the VSS_PA pin and the center pad:
We do not know anything but what is in the datasheet unfortunately, but this is a quite common way to tune the center frequency of some antennas. A few pF is usually a good starting point, you will have to measure the VSWR using a VNA and test various combinations and see how the center frequency of the antenna is affected. If you do not have a VNA both Johanson and we can do this for you.

Best regards,

Andreas